Electric-arc lamp



(No Model.) 3 Sheets-Sheet 1. E. THOMSON.

v ELECTRIC ARC LAMP. No. 478,145. Patented July 5, 1892.

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ELECTRIC ARC LAMP. No. 478,145. Patented July 5, 1892.

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(No Model.) 3 Sheets-Sheet 3.

- E. THOMSON. ELEGTRIG ARC LAMP? No. 478,145. Patented July 5, 1892.

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ELIHU THOMSON, OF LYNN, MASSACHUSETTS, ASSIGNOR TO THE THOMSON- HOUSTONELECTRIC COMPANY, OF CONNECTICUT.

ELECTRIC-ARC LAMP.

SPECIFICATION forming part of Letters Patent No. 478,145, dated July 5,1892. Application filed March 22, 1890- Serial No. 344,936- (No model.)

To all whom it may concern.-

Be it known that I, ELIHU THOMSON, a citizen of the United States,residing at Lynn, county of Essex, State of Massachusetts, have inventedcertain new and useful Improvements in Electric-Arc Lamps, of which thefollowing is a specification.

My invention relates to an improved mechanism for feeding carbons of anarc lamp.

m In principle it consists in the application of a constantly-runningelectric motor whose speed depends directly on the condition of the arc,the motion being accelerated when the feed of the carbon is to takeplace and retarded when a separation of the carbons is to take place.The reverse process will be used when the motor is in series with theare from that employed when it is in shunt. During the normal conditionof the carbons and the are no feeding is going on, the motor thenrunning at a normal speed and not actuating the carbons either way. Anysuitable mechanism for accomplishing this result may be used; butpreferably I combine with the motor a centrifugal governor orspeedresponsive device, which, when the speed of the motor is above acertain normal point, gears the motor with mechanism for moving thecarbons in one direction and when it is 0 below the normal point gearsthe motor with the mechanism for moving it in the other direction.

My invention is especially applicable to are lamps used with reflectorsin which the are is focused positively and in which it is desirable thatthe movements of the carbons shall be steady and positive.

Search -lamps in particular may be constructed embodying my invention,since by 0 it one is able to control a lamp of large power, so as tosecure a steady normal are without manual attention, the practice havinghitherto been to operate such lamps by hand and adjust the distance ofthe carbons apart by 5 the eye.

I will proceed to describe the invention by reference to the figures ofthe drawings.

Figure 1 is an elevation of a focusing-lamp suitable for search-lightpurposes embodying the invention, the upper part being at an angle toaccommodate the figures to the sheet. Fig. 2 is an elevation of a lampof the ordinary kind in which there is a non-focusing are. In this casethe mechanism feeds only the upper carbon. Figs. 3, at, 5, and (5 showelectrical connections which may be made in varying the conditions underwhich my invention is put into use.

In Fig. 1, E E are the carbon electrodes of an arc lamp, constructed, asshown, to be separated and approached by the rotation of a screw S innuts N N, the upper part of the screw having a right-hand thread and thelower part a left-hand thread of half the pitch, so as to feed the uppercarbon nearly double the distance traversed in the same time by thelower. The nuts N-N are carried on a guide-rod G and sustain the carbonsby adjustable brackets aflixed in the usual manner. Of course it will beunderstood that the carbons have to be insulated and contact devicesapplied to convey the current to them, the lower carbon being shown inthis instance as insulated at I from the nut N, which carries it, whilethe current passes to the upper electrode from the general frame-work ofthe lamp. The lower electrode E passes through an insulated boxVand isconnected with the binding-post V, to which the circuit-wires areattached. The beveled gear-wheel B is carried on the screw-shaft S,which shaft turns in a suitable bearing preventing end motion. Thegear-wheel B has a correspondingly-beveled wheel A gearing with it,which is carried on a horizontal shaft, upon which shaft is also carrieda wor1n-wheel D, into which the worm of the screw \V engages. The wormIVis carried on a vertical shaft, which also bears the friction-wheel F,with a beveled lower face. This friction-wheel is preferably made ofsome 0 material like compressed leather and cut to form. It rests inbetween two other friction wheels or pinions J and K, one or the otherof which may be thrown into engagement with the friction-wheel F,according to 5 the position of the governing appliance I'l, carried on ashaft of motor M. The frictionwheels J and K are put upon a sleeve whichslides along the shaft on a spline, and the governor II is constructedto expand by centrifurco gal action against a spring 13 and to draw thesleeve and wheels J and K along with it, so that on a high speed K willbe thrown into engagement with F and on a low speed J will beinengagement. On an intermediate speed both the parts J and K will justclear the disk F, neither of them turning it. The electric motor H isfurnished with a commutator and an armature and field-magnet wound tocarry the necessary current. The connections of these portions will bedescribed farther 011.

It will be readily understood from the mechanism thus shown that if themotor runs ata definite normal speed it will neither feed nor retractthe carbons E E to or from one another, but that if it rises or falls inspeed one or the other of the pinions J or K will be thrown intoengagement with the beveled friction-wheel F and turn the screw XV,giving motion to the wheelsD and A the latter of which drives the gear13 of the screw-shaft S to approximate or retract the-carbons E E.

In Fig. 2 the corresponding parts are designated by the same letters andwill be readily understood. The only difference is that the screw-shaftS is replaced by a rack-shaft S, carrying the upper carbon E, and theworm W engages with the vheel B, on the shaft of which is carried thepinion of the rack-shaft. The electromotor M, as before, controls theaction of the governor II to throw one of the pinions J or K intocontact with the wheel F.

The connections shown in Fig. 2 and in diagram Fig. 3 are as follows:The current enters at a, and a branch is taken therefrom through a finewire or shunt winding on the field Q of the motor M. The circuit from ais also branched through the armature of the motor M and through aresistance R, whose amount can be varied in adjusting the lamp. Thecurrent leaving the resistance R passes directly to the rack-rod S andto the upper carbon E, thence to the lower carbon E and out at b,whilethe field-magnet winding shunts the arc.

Assuming the lamp to be connected across the mains of aconstant-potential circuit, a conditionto which the positive actionassured by my invention is especially adapted, the carbons when togetherwould be traversed by a considerable current, and therefore the armatureof the motor M will also be traversed by a considerable current, whilethe field Q will be comparatively weak. This will set the motor runningat once at a high speed and will bring into engagement the pinion K toseparate the carbons by rotation of F. A counter electro-motive forcewill be set up in the armature of the motor M, which tends to keep outthe current and turn it into the resistance R. If now by an elongationof the are by combustion the field be increased, being a shunt aroundthe are, this counter electro-motive force will still'further reduce thecurrent flowing in the armature of the motor and the speed will fall,which will bring the pinion J into contact with F and positively feedthe carbons toward each other by a reverse motion to that whichseparated them. These actions will be repeated at intervals, asrequired.

Fig. at is a modification of the connections in which the arc is incircuit with a dead-resistance Y when it is used on a constant-potentialcircuit. This deadresistance is a steadier of the current, and the motoris connected around the circuit, so as to shunt the are. In this casevariations of speed of the motor will occur by variation of the distanceapart of the carbons, and these variations may be utilized, as pointedout above, to regulate the position of the carbons.

In Fig. 5 the motor M is in series with the carbons E E, the currentthrough which varies, and it will be understood that here the operationwill be a response to increasing or decreasing current in thelamp-circuit, the connections being such as to cause a decreasingcurrent to feed the carbons by affecting the speed of the motorcorrespondingly and an increasing current to separate them, the lampbeing adapted to work on constant-potential circuits, as before.

Fig. 6 shows the motor having a compound field, part of it Q in shunt tothe circuit and part of it Q, in series with the armature, so that theaction is now one of differentiation, a response of the motor takingplace on an increase or diminution of the current in the lamp-circuit.These two influences act together to cause the variations of speed inthe motor which is used by the governing appliances before described toregulate the position of the carbons.

That I claim as new, and desire to secure by Letters Patent, is-

1. The combination, with an arc-lamp carbon, of a constantly-runnin gmotor controlled by and responsive to the current or electromotive forcebetween the terminals of the are or lamp and a speed-responsive deviceconnecting the carbon with the motor, so as to cause the motor tooperate the carbon on a variation from normal speed.

2. The combination, with an arc-light carbon, of an electric motorconstantly in operation and a speed-responsive device connecting saidcarbon with the motor, so as to be actuated thereby upon a variationfrom the normal speed of the motor.

3. The combination, with an arc-light car bon, of an electric motor onthe same circuit and depending upon the electrical conditions of the arcand a speed-responsive device actuated by the said motor and adapted tocon nect the carbon with the motor, so as to be actuated thereby upon avariation from the normal speed of the motor.

4. The combination, with an arc'light carbon, of operating mechanismtherefor, an electric motor constantly in operation and depending uponthe electrical condition of the arc, and a speed-responsive devicedriven by said motor and adapted to connect the said motor with the saidmechanism upon avariation from the normal speed of the motor.

5. The combination, with two arc-light carbons,ofa common actuatingmechanism therefor, an electric motor actuated constantly and dependingupon the condition of the arc, and a speed-responsive device adapted toconnect the motor with the said mechanism on a variation from the normalspeed of the motor.

6. The combination, with an arc-light carbon, of an electric motorconstantlyin operation, speed-reducing mechanism through which the motormay act upon said carbon, and a speed-responsive device for mechanicallyconnecting the motor and the carbon through said mechanism upon avariation from the normal speed of the motor.

7. The combination, with an arc-light carbon,of actuating mechanismtherefor having a friction-wheel for driving the same, an electricmotor, two pinions driven by the motor, and a speed responsive deviceadapted to bring one or the other of said pinions in contact with saidfriction-wheel upon a variation from the normal speed of the motor.

8. The combination, with two arc-lightcarbons, of a shaft having twoscrew-threads thereon of different pitch, a nut connecting each of thesaid carbons with the two screwthreads, respectively, an electric motorin continuous operation, and a speed-responsive device connecting thesaid motor with the said shaft upon a variation from its normal speed.

9. The combination, with a constant-potential circuit, of an arc lampincluded therein, a constantly-running electric motor having drivingconnections with a carbon of said lamp and having its armature incircuit with the arc, and speed-responsive devices connected to suchmotor and changing or reversing its driving relation to said carbon.

10. The combination,with a constant-potential circuit, of an arc lampincluded therein, an electric motor also included in said circuit, and aspeed-responsive device connecting the said motor with the said carbonseither to approach or to separate them upon a variation from the normalspeed of the motor.

ELII'IU THOMSON.

Witnesses:

JOHN W. GIBBONEY, W. J. PHUNSTEAD.

